1. Field of the Invention
This invention relates to a separating device suitable for use in treating a particle containing gas flow stream to separate particles from the gas or to clean the gas of particles.
2. Description of Background Art
The kind of separating device to which the invention relates, can more precisely be described as a vortex tube particle recovery device or as a vortex tube gas cleaning device, depending on which aspect of its operation emphasis is placed. This invention more particularly has in mind the cleaning of gas, especially the cleaning of air. Thus, generally, the term vortex tube gas cleaning device will be used in the specification. However, the invention covers also the particle recovery aspect.
3. Summary and Objects of the Invention
For convenience, references to direction, more specifically "downstream" and "upstream", must be interpreted in relation to the normal direction of flow of gas through the device.
More specifically, the invention relates to a vortex tube gas cleaning device or particle recovery device suitable for use in treating a particle containing gas flow stream to clean the gas of particles or to recover particles from the gas, the device comprising
an outer round tube having an inlet at one end which will be an upstream end in use and an opposed end which will be a downstream end in use; PA1 an axially arranged vortex or rotating flow generator in the tube downstream of the inlet; PA1 a separation region downstream of the vortex generator; PA1 an inner round extraction tube, arranged concentrically within the outer round tube toward the downstream end of said outer round tube, said inner round tube having an inlet at a predetermined axial position corresponding to the end of the separation region, and central outlet means at a downstream end thereof; PA1 a peripheral outlet region annularly intermediate said outer round tube and said inner round extraction tube; PA1 a central outlet region formed by said inner round extraction tube; and PA1 outlet means downstream of the peripheral outlet region; PA1 an acceleration-deceleration formation in the form of a ring having, in series, a divergent portion, a crown, and a convergent portion, the ring being located annularly around the inner round extraction tube and spatially tot he inlet of the inner round extraction tube, to form in the peripheral outlet region, in series, and spaced from the inlet of the inner round extraction tube, an annular acceleration region, an annular orifice and an annular diffuser region. PA1 an outer round tube having an inlet at one end which will be an upstream end in use and an opposed end which will be a downstream end in use; PA1 an axially arranged vortex generator in the tube downstream of the inlet; PA1 a separation region downstream of the vortex generator; PA1 an inner round extraction tube, arranged concentrically within the outer round tube toward the downstream end of said outer round tube, said inner round tube having an inlet at a predetermined axial position corresponding to the end of the separation region, and central outlet means at a downstream end thereof; PA1 a peripheral outlet region annularly intermediate said outer round tube and said inner round extraction tube; PA1 a central outlet region formed by said inner round extraction tube; and PA1 outlet means downstream of the peripheral outlet region; the method of flow comprising: PA1 introducing the particle containing gas flow stream axially into the outer round tube via said inlet; PA1 inducing rotating flow in the particle containing gas flow stream by guiding the gas flow stream through the vortex generator; PA1 allowing the particles to migrate toward and to concentrate toward the outer periphery of the flow stream while the flow stream flows through the vortex generator and the separation region; PA1 guiding a particle depleted portion of the flow stream, toward the center of the tube, via the central outlet region through he central outlet means; PA1 guiding a particle enriched portion of the flow stream, toward the outer periphery of the tube, via the peripheral outlet region through the outlet means including the steps of contracting and accelerating the particle enriched portion of the flow stream in the annular acceleration region and transforming dynamic pressure in the particle enriched flow stream into static pressure by allowing the particle enriched flow stream to diffuse in the annular diffuser region.
In accordance with the invention, in treating a particle containing gas flow stream in a device of the kind described, there is provided an apparatus having a method of flow comprising
The acceleration may be between about 50% and about 300%, preferably about 100%.
The method may include the further step of gaining static pressure in the enriched particle flow stream at the expense of kinetic or dynamic pressure by allowing the flow stream to diffuse or decelerate in a diffuser in the peripheral outlet region downstream of the acceleration region.
Accordingly, the invention extends to a vortex tube gas cleaning device or particle recovery device of the kind described, in which at least a portion of the peripheral outlet region converges or contracts in respect of flow area to form an acceleration region to induce accelerating flow in use.
The convergence or contraction may be formed by a divergence or flaring of the inner round extraction tube. The included angle of flaring or divergence of the inner round extraction tube may be between about 60.degree. and about 135.degree., preferably about 90.degree..
The ratio of the flow areas respectively immediately upstream and downstream of the acceleration region may be between about 1.5:1 and about 4:1, preferably about 2:1.
By way of development, a portion of the peripheral outlet region, downstream of the acceleration region, may be in the form of a diffuser arranged to decelerate the particle enriched flow stream.
Further by way of development, the divergence or flaring of the inner round extraction tube may commence spatially downstream of the inlet to the inner round extraction tube, said inlet being in the form of a mouth of aerodynamic shape which has a sharp leading edge and a lip curving inwardly from the leading edge, the radius of curvature of the lip being larger than the thickness of the lip such that a tangent to the lip at the leading edge and extending inwardly and downstream, forms an acute angle with the inner periphery of the inner tube. Preferably, the acute angle lies in the range of 30.degree. to 50.degree..
Further scope of applicability of the present invention will become apparent form the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.